This invention relates to topical compositions for application to human skin and to their use in improving the condition and appearance of skin.
Skin is subject to deterioration through dermatological disorders, environmental abuse (wind, air conditioning, and central heating) or through the normal ageing process (chronoageing) which may be accelerated by exposure of skin to sun (photoageing). In recent years the demand for cosmetic compositions and cosmetic methods for improving the appearance and condition of skin has grown enormously.
Consumers are increasingly seeking anti-ageing cosmetic products that treat or delay the visible signs of chronoageing and photoageing skin such as wrinkles, lines, sagging, hyperpigmentation and age spots.
Consumers also frequently seek other benefits from cosmetic products in addition to anti-ageing. The concept of sensitive skin has also raised the consumer demand for cosmetic products that improve the appearance and condition of sensitive, dry and/or flaky skin and to soothe red, and/or irritated skin. Consumers also desire cosmetic products that have an oil/sebum control effect.
Many people are concerned with the degree of pigmentation of their skin. For example, people with age spots or freckles may wish such pigmented spots to be less pronounced. Others may wish to reduce the skin darkening caused by exposure to sunlight or to lighten their natural skin colour. To meet this need many attempts have been made to develop products that reduce the pigment production in the melanocytes. However, the substances thus far identified tend to have undesirable side effects, e.g. skin irritation.
Consequently such substances are not suitable for cosmetic use or they can only be applied at a concentration at which their skin lightening effect is less than desired. Using a combination of different skin lightening substances may be considered to reduce adverse side effects but there is a substantial risk that by using such a combination the skin lightening is reduced as well due to competition effects. Therefore there is a need for improvement in the effectiveness of cosmetic skin lightening products particularly, such that they do not irritate the skin.
J07277939 describes a skin care composition for improving skin ageing and skin inflammation that contains (A) Flor de Manita and (B) at least 1 of active selected from oxygen removers, antioxidants, cell activators, anti-inflammatories, tyrosinase inhibitors and moisture-retaining agents. Amongst the many options of ingredients described for component B are quercetin, quercitolin, catechin, gallic acid, gamma-linolenic acid, and eicosapentaenoic acid.
J05271046 describes a skin lightening composition that contains an unsaturated fatty acid having 18 to 22 carbons and two or more unsaturated bonds, such as linoleic and arachidonic acid, and a polyphenol.
WO99/26588 describes anti-ageing skin care formulations comprising conjugated linoleic acid and which may optionally contain conventional sunscreens, such as benzophenones.
The art discussed above does not disclose the specific synergistic combination of conjugated linoleic acid with a phenolic compound (that is not a sunscreen) nor the use of such a specific combination for treating wrinkles, sensitive skin, dry skin, controlling oil/sebum secretion, or lightening skin. Phenolic compounds which act as a sunscreen are specifically excluded from the scope of the present invention.
A sunscreen is herein defined as an ingredient that provides a sun protection factor (SPF) of at least 2 when tested in a cosmetic product formulation on human skin using the standardised protocol described in the Food and Drug Administration Monograph Sunscreen Drug Products for Over-The-Counter Human Use; Final Monograph published in the Federal Register Volume 64, No 98, May 21, 1999, pages 27666 to 27691.
We have now found that effective treatment and prevention of normal but cosmestically undesirable skin conditions due to chronoageing or photoageing, such as wrinkles, lines, sagging, hyperpigmentation and age spots, may be obtained through the application of cosmetic compositions to the skin which comprise conjugated linoleic acid and/or derivatives thereof in combination with a phenolic compound with the proviso that the phenolic compound is not a sunscreen. We have also found that the use of such cosmetic compositions advantageously provides further skin benefits in addition to anti-ageing such as soothing sensitive and/or irritated skin, controlling oil/sebum secretion and for lightening the skin.
According to a first aspect of the present invention there is provided a topical composition comprising:
(a) conjugated linoleic acid and/or derivatives thereof;
(b) a phenolic compound or mixtures thereof; and
(c) a dermatologically acceptable vehicle;
with the proviso that the phenolic compound is not a sunscreen.
According to a second aspect of the present invention there is provided a cosmetic method of providing at least one skin care benefit selected from: treating/preventing wrinkling, sagging, dry, aged and/or photodamaged skin; boosting collagen deposition in skin, boosting decorin production in skin, enhancing tissue repair; soothing irritated, red and/or sensitive skin; improving skin texture, smoothness and/or firmness; lightening skin; or controlling oil/sebum secretion, the method comprising applying to the skin a cosmetic composition as described above.
The present invention also encompasses the use of the inventive compositions for providing at least one skin care benefit selected from treating/preventing wrinkling, sagging, aged and/or photodamaged skin; boosting collagen deposition in skin, boosting decorin production in skin, enhancing tissue repair; soothing irritated, red and/or sensitive skin; improving skin texture, smoothness and/or firmness; lightening skin; and controlling oil/sebum secretion.
According to a still further aspect of the present invention there is provided the use of conjugated linoleic acid and/or derivatives thereof in combination with a phenolic compound or mixtures thereof, with the proviso that the phenolic compound is not a sunscreen, in a cosmetic topical composition for providing at least one cosmetic skin care benefit selected from treating/preventing wrinkling, sagging, aged and/or photodamaged skin; boosting collagen deposition in skin, boosting decorin production in skin, enhancing tissue repair; soothing irritated, red and/or sensitive skin; improving skin texture, smoothness and/or firmness; lightening skin; and controlling oil/sebum secretion.
The inventive compositions, methods and uses thus provide anti-ageing benefits which result in the promotion of smooth and supple skin with improved elasticity and a reduced or delayed appearance of wrinkles and aged skin, with improved skin colour. A general improvement in the appearance, texture and condition, in particular with respect to the radiance, clarity, and general youthful appearance of skin is achieved. The inventive compositions, methods and uses are also beneficial for soothing and calming sensitive and/or irritated skin, for lightening skin and for controlling oil/sebum secretion. Thus the present invention advantageously provides a wide range of skin care benefits.
The term treating as used herein includes within its scope reducing, delaying and/or preventing the above mentioned normal but cosmetically undesirable, skin conditions such as wrinkled, aged, and/or photodamaged, and/or irritated skin and generally enhancing the quality of skin and improving its appearance and texture by preventing or reducing irritation, wrinkling and increasing flexibility, firmness, smoothness, suppleness and elasticity of the skin. The compositions, methods and uses according to the invention may be useful for improving skin which is already in a wrinkled, aged, photodamaged, irritated condition or for treating youthful skin to prevent or reduce those aforementioned undesirable changes due to the normal ageing/photo ageing process.
Conjugated Linoleic Acids
Conjugated linoleic acid (hereinafter referred to as CLA) is a diunsaturated long chain (C18) fatty acid. CLA comprises a group of positional and geometric isomers of linoleic acid in which various configurations of cis and trans double bonds at positions (6, 8), (7, 9), (8, 10), (9, 11), (10, 12) or (11, 13) are possible. Thus twenty-four different isomers of CLA exist.
The invention also includes derivatives of the free acid which thus comprise conjugated linoleic acid moieties. Preferable derivatives include those derived from substitution of the carboxyl group of the acid, such as esters (e.g. triglyceride esters, monoglyceride esters, diglyceride esters, phosphoesters), amides (e.g. ceramide derivatives), salts (e.g. alkali metal and alkali earth metal salts, ammonium salts); and/or those derived from substitution of the C18 carbon chain, such as alpha hydroxy and/or beta hydroxy derivatives.
In the case of triglyceride ester derivatives, all positional isomers of CLA substituents on the glycerol backbone are included. The triglycerides must contain at least one CLA moiety. For example, of the three esterifiable positions on the glycerol backbone, the 1 and 2 positions may be esterified with CLA and by another lipid at position 3 or as an alternative, the glycerol backbone could be esterified by CLA at the 1 and 3 positions with another lipid at position 2.
The most preferred isomers of CLA for use in the present invention are the cis 9 trans 11 (c9 t11) or trans 10 cis 12 (t10 c12) isomer. Preferably at least 1% by weight of the total CLA (and/or CLA moieties) present in the composition is in the form of the c9, t11 and/or t10, c12 isomer. More preferably at least 20% and most preferably at least 40%, by weight of the total CLA and/or CLA moieties present in the composition, is in the form of the c9, t11 isomer and/or t10, c12 isomer. In a particularly preferred embodiment the conjugated linoleic acid is enriched in the c9 t11 or the t10, c12 isomer. By enriched is meant that at least 50% by weight of the total CLA and/or CLA moieties present in the composition is in the form of the cis 9, trans 11 or the trans 10 cis 12 isomerxe2x80x94preferably, at least 70%, more preferably at least 80%, and most preferably at least 90% by weight of the total CLA and/or CLA moieties present in the composition, are in the form of the c9, t11 isomer or the t10 c12 isomer.
The CLA and/or derivatives thereof comprising CLA moieties according to the present invention are commercially available as oils that are rich in conjugated linoleic acid triglyceride such as Tung oil or as dehydrated castor oil (Unichema). A mix isomer product is available from Sigma and a c9 t11 isomer enriched CLA is available from Matreya inc. Alternatively CLA according to the preferred embodiments of the present invention may be prepared according to the method disclosed in WO 97/18320 whose contents are incorporated herein by reference. A preferred method of preparation is disclosed in Example 1 and 2 below.
Wherever the term conjugated linoleic acid or CLA is used in this specification it is to be understood that the derivatives thereof comprising CLA moieties are also included. CLA moieties refers to CLA fatty acyl portion(s) of a CLA derivative.
The CLA, to be employed in accordance with the present invention is present in the topical composition in an effective amount. Normally the total amount of the active is present in an amount between 0.0001% and 50% by weight of the composition. More preferably the amount is from 0.01% to 10% and most preferably from 0.1% to 5% in order to maximise benefits at a minimum cost.
Phenolic Compounds
Phenolic compounds can be divided into at least 10 different classes depending on their basic chemical structure. The compounds include simple phenols (C6), benzoquinones (C6), phenolic acids (C6xe2x80x94C1), acetophenones (C6xe2x80x94C2), phenylacetic acids (C6xe2x80x94C2), hydroxycinnamic acids (C6xe2x80x94C3), phenylpropenes (C6xe2x80x94C3), coumarins, isocoumarins (C6xe2x80x94C3), chromones (C6xe2x80x94C3), naftoquinones (C6xe2x80x94C4), xanthones (C6xe2x80x94C1xe2x80x94C6), stilbenes (C6xe2x80x94C2xe2x80x94C6), flavonoids (C6xe2x80x94C3xe2x80x94C6), lignans, neolignans (C6xe2x80x94C3)2 and lignins (C6xe2x80x94C3)n.
The term flavonoids represents a very large group of compounds consisting of two aromatic rings joined by a three carbon unit, e.g. C6xe2x80x94C3xe2x80x94C6. The family of flavonoids includes isoflavonoids, monomeric flavonols, dihydroflavonoids, catechins, epicatechins (e.g. laurones), leucoanthocyanadins, proanthocyanadins, anthocyanadins, flavones, flavonones, chalcones, dihydrochalcones, isoflavones, neoflavones, aurones, flavan 3 ols, flavan 3 ols, and anthrocyanins. The term isoflavanoids also includes isoflavones, pterocarpans, isoflavonones, rotenoids, isoflavans and isoflavanols.
The preferred phenolic compounds for use in the compositions of the present invention are flavonoids including flavonones such as naringenin, flavonols such as quercetin, catechin (e.g. epigallocatechingallate, EGCG), isoflavonoids such as daidzein, genistein, lycetin, and also phenolic acids, such as gallic acid, and the green tea polyphenols.
Quercetin, naringenin, daidzein, genistein, EGCG and green tea polyphenols may be obtained from Sigma. Plant extracts containing the phenolic compounds are also suitable for use in the present invention. For example, rutin, evening primrose, onion, citrus species contain quercetin and naringenin, soy contains daidzein and genistein and green tea varieties such as Camellia sinensis and assamica contain EGCG and green tea polyphenols.
Phenolic compounds that are specifically excluded from the present invention are those which are conventionally used as sunscreens such as para-amino benzoic acid and benzophenones.
The phenolic compound or mixtures thereof is employed in the inventive composition in an amount of from about 0.01% to about 10%, preferably in an amount of from about 10% to about 1%, most preferably in an amount of from about 0.1% to about 5%.
Dermatologically Acceptable Vehicle
The composition used according to the invention also comprises a dermatologically/cosmetically acceptable vehicle to act as a dilutant, dispersant or carrier for the actives. The vehicle may comprise materials commonly employed in skin care products such as water, liquid or solid emollients, silicone oils, emulsifiers, solvents, humectants, thickeners, powders, propellants and the like.
The vehicle will usually form from 5% to 99.9%, preferably from 25% to 80% by weight of the composition, and can, in the absence of other cosmetic adjuncts, form the balance of the composition.
Optional Skin Benefit Materials and Cosmetic Adjuncts
Besides the actives, other specific skin-benefit actives such as sunscreens, skin lightening agents, skin tanning agents may also be included. The vehicle may also further include adjuncts such as antioxidants, perfumes, opacifiers, preservatives, colourants and buffers.
Product Preparation, Form, Use and Packaging
To prepare the topical composition used in the method of the present invention, the usual manner for preparing skin care products may be employed. The active components are generally incorporated in a dermatologically/cosmetically acceptable carrier in conventional manner. The active components can suitably first be dissolved or dispersed in a portion of the water or another solvent or liquid to be incorporated in the composition. The preferred compositions are oil-in-water or water-in-oil or water-in-oil-in-water emulsions.
The composition may be in the form of conventional skin-care products such as a cream, gel or lotion, capsules or the like. The composition can also be in the form of a so-called wash-off product e.g. a bath or shower gel, possibly containing a delivery system for the actives to promote adherence to the skin during rinsing. Most preferably the product is a leave-on product; a product to be applied to the skin without a deliberate rinsing step soon after its application to the skin.
The composition may packaged in any suitable manner such as in a jar, a bottle, tube, roll-ball, or the like, in the conventional manner. It is also envisaged that the inventive compositions could be packaged as a kit of two separate compositions one containing the conjugated linoleic acid and the second containing the phenolic compound, to be applied to the skin simultaneously or consecutively.
The composition according to the present invention may also be formulated into a form suitable for oral ingestion such as a capsule, tablet or similar.
The method of the present invention may be carried out one or more times daily to the skin which requires treatment. The improvement in skin appearance will usually become visible after 3 to 6 months, depending on skin condition, the concentration of the active components used in the inventive method, the amount of composition used and the frequency with which it is applied. In general, a small quantity of the composition, for example from 0.1 to 5 ml is applied to the skin from a suitable container or applicator and spread over and/or rubbed into the skin using the hands or fingers or a suitable device. A rinsing step may optionally follow depending on whether the composition is formulated as a leave-on or a rinse-off product.
In order that the present invention may be more readily understood, the following examples are given, by way of illustration only.